Tag: Sun

This morning, the sun erupted with the most powerful solar flare in a decade, blasting the Earth’s upper atmosphere with energetic X-ray and extreme ultraviolet (EUV) radiation.

The flare was triggered by intense magnetic activity over an active region called AR2673 that has been roiling with sunspot activity for days, threatening an uptick in space weather activity. As promised, that space weather brought an explosive event at 1202 UTC (8:02 a.m. PT) that ionized the Earth’s upper atmosphere and causing a shortwave radio blackout over Europe, Africa and the Atlantic Ocean, reports Spaceweather.com.

Radio blackout map: When the Earth’s ionosphere is energized by X-ray and EUV radiation from solar flares, certain radio frequencies are absorbed by increased ionization of certain layers of the atmosphere, posing issues for global radio communications (NOAA)

The powerful X9.3-class flare came after an earlier X2.2 blast from the same active region, a significant flare in itself. X-class flares are the most powerful type of solar flares.

The electromagnetic radiation emitted by flaring events affect the Earth’s ionosphere immediately, but now space weather forecasters are on the lookout for a more delayed impact of this eruption.

The powerful X9-class solar flare erupted from the active region (AR) 2673, a large cluster of sunspots — seen here by NASA’s Solar Dynamics Observatory (NASA/SDO)

Solar flares can create magnetic instabilities that may launch coronal mass ejections (CMEs) — basically vast magnetized bubbles of energetic solar plasma — into interplanetary space. Depending on the conditions, these CMEs may take hours or days to reach Earth (if they are Earth-directed) and can generate geomagnetic storms should they collide and interact with our planet’s global magnetic field.

A photo of the 2012 annular eclipse from Malibu, Calif., using an old digital camera and solar filter (Ian O’Neill)

The U.S. media is currently saturated with hot takes, histories, weird facts, “how to’s” and weather reports around the Great American Eclipse that will glide across the continent on Monday (yes, THIS Monday, it’s finally here). But, today, one news report stood out from the crowd:

On reading the NBC News report (that was penned by an unknown Reuters writer), it is as tone deaf as the headline.

“American employers will see at least $694 million in missing output for the roughly 20 minutes that outplacement firm Challenger, Gray & Christmas estimates workers will take out of their workday on Monday to stretch their legs, head outside the office and gaze at the nearly two-and-a-half minute eclipse,” they write.

“Stretch their legs” for a “two-and-a-half minute eclipse,” — wow, what a waste of time. Worse than that, “[m]any people may take even longer to set up their telescopes or special viewing glasses, or simply take off for the day.” Unbelievable. Those skiving freeloaders.

How dare they take some time to step away from their computer screens to take a little time to gaze in awe at the most beautiful and rare natural celestial event to occur on our planet.

How dare they put pressure on the U.S. economy by bleeding hundreds of millions of dollars in lost revenue from the monstrous multi-trillion dollar consumerist machine.

How dare they be moved to tears as the moon completely blocks the sun, an event that has caused fear, suspicion, omen, wonderment, joy, inspiration, excitement and unadulterated passion throughout the history of our species.

How dare th— oh wait a minute. The lede appears to be buried:

“Compared to the amount of wages being paid to an employee over a course of a year, it is very small,” Challenger said. “It’s not going to show up in any type of macroeconomic data.”

So what you’re staying is, $700 million won’t even show up as a blip in economic analyses? Tell me more.

“It also pales when compared with the myriad other distractions in the modern workplace, such as March Madness, Cyber Monday, and the Monday after the Super Bowl,” they write. Well, whatdoyouknow, the Super Bowl is a distraction too? Those monsters.

So what you’re saying is, this isn’t really news. As a science news producer, I completely understand the pressures to keep up with the news cycle and finding fresh takes on tired stories (and let’s face it, 2017 has seen its fair share of eclipse articles). But for this particular angle, I think I would have most likely relegated the “lost” revenue to a footnote in a more informative and less clickbaity piece.

Monday’s eclipse will do untold good to this nation. The U.S. is going through a tumultuous stage in its young history, to put it mildly. This nation needs perspective to overcome the ineptitude, anti-science rhetoric and messages of segregation coming from its government; it needs an event that will be enjoyed by everyone, not just a fortunate subsection of society or the elite. The eclipse will inspire millions of people to look up (safely!) and ponder why is it that our planet’s only natural satellite can exactly fit into the disk of the sun.

Astronomy is an accessible gateway to the sciences and the eclipse will inspire, catalyzing many young minds to consider a future in STEM fields of study. This will enrich society in a myriad of ways and the economic gains from events such as Monday’s eclipse will make “$700 million” look like a piss in a swimming pool.

So, you know what? I’m glad this eclipse will “cost” the U.S. $700 million — I see it as an accidental investment in the future of this nation, a healthy nation that will hopefully put the antiscience stance of its current leaders behind it.

During the formation of the solar system, when the planets were molten messes and asteroid collisions (or “mudball” collisions, possibly) were commonplace, chunks of icy debris were flung away from the chaos surrounding our messy young star and relegated to a lifetime of solitude in the furthest-most reaches of the sun’s gravitational influence. This debris eventually settled and formed what is known as the Oort Cloud, a mysterious spherical shell of countless mountain-sized objects located nearly 200 billion miles away.

As the Oort Cloud is so distant, and there are no telescopes on Earth (or off-Earth) that can resolve these objects, we can only guess at how many icy lumps are out there lurking in the dark. But should a passing star cause a gravitational wobble in that region, a few of those ancient objects may be knocked off their delicate gravitational perches and they take the plunge back toward the sun, becoming what we humans call “long-period comets.” Only when we see these comets can we get a hint of the population of the Oort Cloud and the nature of long-period comets. But, as many of these deep space vagabonds have orbital periods of hundreds to millions of years, they are notoriously difficult to track.

A long period comet may appear in the sky tomorrow, but it may not return in Earth’s skies until the age of humanity is long gone and intelligent cockroaches roam the planet. It’s hard to keep track of comets with orbital periods longer than our lifespans, let alone the lifespan of our civilization.

So it may not come as a surprise that astronomers have woefully underestimated the number of long-period comets, according to a new study using observations from NASA’s Wide-field Infrared Survey Explorer, or WISE, mission. But not only that, these things are a lot bigger than we thought.

The study, which has been published in The Astrophysical Journal, found that WISE had detected three to five times more long-period comets pass the sun over an eight-month period than expected and revealed that there are seven-times more long-period comets at least 1 kilometer across.

“The number of comets speaks to the amount of material left over from the solar system’s formation,” said lead author James Bauer, of the University of Maryland, College Park, in a NASA statement. “We now know that there are more relatively large chunks of ancient material coming from the Oort Cloud than we thought.”

WISE completed its primary mission in 2011, but has now embarked on a new mission to look out for dim asteroids and comets that stray close to Earth, called NEOWISE (NEO is for “Near-Earth objects”). During its primary mission, WISE was tasked to observe the universe in infrared wavelengths — revealing the otherwise hidden secrets of distant galaxies and the faint glow of mysterious objects traveling through the solar system. Among these objects were a surprising number of long-period comets, objects that WISE was uniquely qualified to characterize.

When comets approach the sun, their ices sublimate, dust is blasted into space and they form their trademark coma (a gaseous “atmosphere”) and tails around their nuclei. These factors obscure the main mass of the comet; astronomers cannot directly see the icy nucleus through the gas and dust — astronomers therefore have a hard time estimating the size of the comet.

To gauge the size of a comet’s nucleus, WISE precisely measures the size of the comet’s coma and subtracts those measurements from dust models to reveal the nucleus’ size (NASA/JPL-Caltech)

But studying WISE’s precision infrared measurements of the comets’ comas, the researchers were able to deduce the actual nuclei sizes by subtracting observational data from theoretical models of the behavior of dust around a comet. In all, 56 long-period comets were studied and compared with observations of 95 “Jupiter family comets” — comets that have short orbital periods around the sun and are gravitationally influenced by Jupiter. This comparison between the two families of comets revealed that long-period comets aren’t only bigger than we expected, these monsters are up to twice the size of Jupiter family comets.

The difference in comet sizes may not come as a surprise — Jupiter family comets have orbital periods less than 20 years and therefore spend much more time being heated by the sun. They lose mass through ice sublimation that, in turn, dislodges dust and other material, ultimately shedding mass. Long-period comets on the other hand are pristine having spend most of their lives in the deep space deep freeze, so they hold onto the material they were born with billions of years ago. Long-period comets are the epitome of primordial.

Naturally, no comet research would be complete without an Existential Reality Check™ and, as you may have guessed, this new research has a dark side.

“Comets travel much faster than asteroids, and some of them are very big,” said co-author Amy Mainzer, principal investigator of the NEOWISE mission at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Studies like this will help us define what kind of hazard long-period comets may pose.”

The Earth and Mars are currently on exact opposite sides of the sun — a celestial situation known as “Mars solar conjunction” — a time when we have no way of directly communicating with satellites and rovers at the Red Planet. So, when the Solar and Heliospheric Observatory (SoHO) spotted a huge (and I mean HUGE) bubble of superheated plasma expand from the solar disk earlier today (July 23), it either meant our nearest star had launched a vast coronal mass ejection directly at Earth or it had sent a CME in the exact opposite direction.

As another solar observatory — the STEREO-A spacecraft — currently has a partial view of the other side of the sun (it orbits ahead of Earth’s orbit, so it can see regions of the sun that are out of view from our perspective), we know that this CME didn’t emanate from the sun’s near side, it was actually launched away from us and Mars will be in for some choppy space weather very soon.

It appears the CME emanated from active region (AR) 2665, a region of intense magnetic activity exhibiting a large sunspot.

CMEs are magnetic bubbles of solar plasma that are ejected at high speed into interplanetary space following a magnetic eruption in the lower corona (the sun’s lower atmosphere). From STEREO-A’s unique vantage point, it appears the CME detected by SoHO was triggered by a powerful solar flare that generated a flash of extreme-ultraviolet radiation (possibly even generating X-rays):

Observation by STEREO-A of the flaring event that likely triggered today’s CME (NASA/STEREO)

When CMEs encounter Earth’s global magnetic field, the radiation environment surrounding our planet increases, posing a hazard for satellites and unprotected astronauts. In addition, if the conditions are right, geomagnetic storms may commence, creating bright aurorae at high latitudes. These storms can overload power grids on the ground, triggering mass blackouts. Predicting when these storms will occur is of paramount importance, so spacecraft such as SoHO, STEREO and others are constantly monitoring our star’s magnetic activity deep inside the corona and throughout the heliosphere.

Mars, however, is a very different beast to Earth in that it doesn’t have a strong global magnetosphere to shield against incoming energetic particles from the sun, which the incoming CME will be delivering very soon. As it lacks a magnetic field, this CME will continue to erode the planet’s thin atmosphere, stripping some of the gases into space. Eons of space weather erosion has removed most of the Martian atmosphere, whereas Earth’s magnetism keeps our atmospheric gases nicely contained.

When NASA and other space agencies check in with their Mars robots after Mars solar conjunction, it will be interesting to see if any recorded the space weather impacts of this particular CME.

There’s no better method to understand how something works than to build it yourself. Although computer simulations can help you avoid blowing up a city block when trying to understand the physics behind a supernova, it’s sometimes just nice to physically model space phenomena in the lab.

So, two Caltech researchers have done just that in an attempt to understand a beautifully elegant, yet frightfully violent, solar phenomenon: coronal loops. These loops of magnetism and plasma dominate the lower corona and are particularly visible during periods of intense solar activity (like, now). Although they may look nice and decorative from a distance, these loops are wonderfully dynamic and are often the sites of some of the most energetic eruptions in our Solar System. Coronal loops spawn solar flares and solar flares can really mess with our hi-tech civilization.

A coronal loop as seen by NASA’s Transition Region and Coronal Explorer (TRACE). Credit: NASA

In an attempt to understand the large-scale dynamics of a coronal loop, Paul Bellan, professor of applied physics at Caltech, and graduate student Eve Stenson built a dinky “coronal loop” of their own (pictured top). Inside a vacuum chamber, the duo hooked up an electromagnet (to create the magnetic “loop”) and then injected hydrogen and nitrogen gas into the two “footpoints” of the loop. Then, they zapped the whole thing with a high-voltage current and voila! a plasma loop — a coronal loop analog — was born.

Although coronal loops on the sun can last hours or even days, this lab-made plasma loop lasted a fraction of a second. But by using a high-speed camera and color filters, the researchers were able to observe the rapid expansion of the magnetic loop and watch the plasma race from one footpoint to the other. Interestingly, the two types of plasma flowed in opposite directions, passing through each other.

The simulation was over in a flash, but they were able to deduce some of the physics behind their plasma loop: “One force expands the arch radius and so lengthens the loop while the other continuously injects plasma from both ends into the loop,” Bellan explained. “This latter force injects just the right amount of plasma to keep the density in the loop constant as it lengthens.” It is hoped that experiments like these will ultimately aid the development of space weather models — after all, it would be useful if we could deduce which coronal loops are ripe to erupt while others live out a quiescent existence.

It’s practical experiments like these that excite me. During my PhD research, my research group simulated steady-state coronal loops in the hope of explaining some of the characteristics of these fascinating solar structures. Of particular interest was to understand how magnetohydrodynamic waves interact with the plasma contained within the huge loops of magnetism. But all my research was based on lines of code to simulate our best ideas on the physical mechanisms at work inside these loops. Although modelling space phenomena is a critical component of science, it’s nice to compare results with experiments that aim to create analogs of large-scale phenomena.

The next test for Bellan and Stenson is to create two plasma loops inside their vacuum chamber to see how they interact. It would be awesome to see if they can initiate reconnection between the loops to see how the plasma contained within reacts. That is, after all, the fundamental trigger of explosive events on the Sun.

A comparison between an observation of the sun using the ATA's 2.75 GHz band (left) and SOHO's 195A filter. Both are near-simultaneous observations on Oct. 1, 2009 (Saint-Hilaire et al., 2011).

And no, “aliens” isn’t the answer.

The Allen Telescope Array (ATA), located near Hat Creek, California, isn’t only used by the SETI Institute to seek out signals from extraterrestrial civilizations. The 42 6.1-meter antennae form an interferometer that can be used for a variety of astronomical studies — in reality, this is the main focus of the project. SETI studies “piggyback” the active astronomical research, passively collecting data.

Due to the radio interferometer’s wide field of view, one surprising use of the ATA is solar astronomy — at radio frequencies. The ATA can be used to simultaneously observe the whole of the solar disk at a range of frequencies rarely studied. As outlined in a recent arXiv publication, a University of California, Berkeley, team of astronomers headed by Pascal Saint-Hilaire have carried out the first ATA solar study, producing images of the sun in a light we rarely see it in (shown above).

According to the paper, active regions were observed at radio and microwave frequencies, spotting the emissions associated with bremsstrahlung — electromagnetic radiation generated by accelerated charged particles caught in intense magnetic fields, a feature typical inside solar active regions. Also, coronal interactions, or gyroresonance, between solar plasma and plasma waves (propagating along magnetic field lines) was detected.

There’s one recurring question I’ve been asking for nearly a decade: Why is the Sun’s corona (its atmosphere) so hot?

When asking this out loud I inevitably get the sarcastic “um, because the Sun is… hot?” reply. Yes, the Sun is hot, really hot, but solar physicists have spent the last half-century trying to understand why the corona is millions of degrees hotter than the solar surface.

After all, if the air surrounding a light bulb was a couple of magnitudes hotter than the bulb’s surface, you’d want to know why that’s the case, right? At first glance, the solar atmosphere is breaking all kinds of thermodynamic laws.

Using the SDO’s high-definition cameras and imagery from the awesome Japanese Hinode solar observatory, features previously invisible to solar astronomers have been resolved. The features in question are known as “spicules.” These small-scale jets inject solar plasma from the solar surface into the lower corona, but until now they’ve been considered too cool to have any appreciable heating effect.

That was until a new type of hot, high-speed spicule was discovered.

“It’s a little jet, then it takes off,” solar physicist Scott McIntosh, of the National Center for Atmospheric Research’s High Altitude Observatory, told Discovery News’ Larry O’Hanlon. “What we basically find is that the connection is the heated blobs of plasma. It’s kind of a missing link that we’ve been looking for since the 1960s.”

These Type II spicules blast hot multi-million degree Kelvin plasma at speeds of 100 to 150 kilometers per second (62 to 93 miles per second) into the corona and then dissipate. What’s more, these aren’t isolated events, they’ve been observed all over the Sun. “This phenomenon is truly ubiquitous and populates the solar wind,” said McIntosh.

While this research provides more clarity on coronal dynamics, McIntosh is keen to point out that Type II spicules probably don’t tell the whole coronal heating story.

NASA’s coronal physics heavyweight James Klimchuk agrees. “It is very nice work, but it is absolutely not the final story on the origin of hot coronal plasma,” he said.

“Based on some simple calculations I have done, spicules account for only a small fraction of the hot plasma.”

Klimchuk favors coronal heating through magnetic stresses in the lower atmosphere generating small reconnection events. Right at the base of the corona, loops of magnetic flux channeling multi-million degree plasma high above the Sun’s chromosphere become stressed and eventually snap. These reconnection processes produce sub-resolution nanoflare events — akin to small explosions releasing energy into the solar plasma, heating it up.

Another heating mechanism — a mechanism I studied during my solar research days (.pdf) — is that of wave heating, when magnetohydrodynamic waves (I studied high-frequency Alfven waves, or ion cyclotron waves) interact with the lower corona, heating it up.

But which heating mechanism injects the most energy into the corona? For now, although there’s plenty of theorized processes (including these new transient Type II spicules), we don’t really know. We can only observe the solar corona from afar, so getting a true grasp on coronal dynamics is very hard. We really need a probe to dive deep into the solar atmosphere and take a measurement in-situ. Although the planned Solar Probe Plus will provide some answers, it may still be some time before we know why the corona is so hot.

But it is most likely that it’s not one coronal heating mechanism, but a combination of the above and, perhaps, a mechanism we haven’t uncovered yet.

This morning, at 08:55 UT, NASA’s Solar Dynamics Observatory (SDO) detected a C3-class flare erupt inside a sunspot cluster. 100,000 kilometers away, deep within the solar atmosphere (the corona), an extended magnetic field filled with cool plasma forming a dark ribbon across the face of the sun (a feature known as a “filament”) erupted at the exact same time.

It seems very likely that both events were connected after a powerful shock wave produced by the flare destabilized the filament, causing the eruption.

A second solar observatory, the Solar and Heliospheric Observatory (SOHO), then spotted a huge coronal mass ejection (CME) blast into space, straight in the direction of Earth. Solar physicists have calculated that this magnetic bubble filled with energetic particles should hit Earth on August 3, so look out for some intense aurorae, a solar storm is on its way…

There I was idly checking out SpaceWeather.com, seeing whether there was any sunspot activity going on… and then I saw this. At first, I assumed it was a highly symmetrical sunspot, but no! It was something far more sinister, but I didn’t recognize the hallmark signature. Neal Wiser saw it instantly and informed me via Twitter. A Borg Cube!

Of course it isn’t a Borg Cube (it’s just missing data), but this little Twitter joviality reminded me of the 2012/Planet X doomsday conspiracy theorists who seem to have the uncanny ability to read anything into, well, anything. Take the observations made by the Solar and Heliospheric Observatory (SOHO) which have been used over and over again as “proof” that UFOs and other scary things are orbiting the Sun, preparing for Armageddon… or the next Star Trek movie.